Methods for matching gain and color for stereoscopic imaging systems

Abstract

Stereoscopic imaging devices may include stereoscopic imagers, stereoscopic displays, and processing circuitry. The processing circuitry may be used to collect auto white balance (AWB) statistics for each image captured by the stereoscopic imager. A stereoscopic imager may include two image modules that may be color calibrated relative to each other or relative to a standard calibrator. AWB statistics may be used by the processing circuitry to determine global, local and spatial offset gain adjustments to provide intensity matched stereoscopic images for display. AWB statistics may be combined by the processing circuitry with color correction offsets determined during color calibration to determine color-transformation matrices for displaying color matched stereoscopic images using the stereoscopic display. Gain and color-transformation corrections may be continuously applied during operation of a stereoscopic imaging device to provide intensity-matched, color-matched stereoscopic images in any lighting condition.

What is claimed is: 
     
       1. A method of producing gain-matched stereoscopic images using a stereoscopic imaging device wherein the stereoscopic imaging device comprises a stereoscopic display, processing circuitry and a stereoscopic imager having a first image module and a second image module, the method comprising:
 capturing a first image with the first image module and a second image with the second image module, wherein the first image and the second image have a common overlapping portion; 
 with the processing circuitry, determining a global gain ratio between the first and second images using the common overlapping portion of the first and second images; 
 with the processing circuitry, determining a local gain ratio using at least one zone in the common overlapping portion of the first and second images; and 
 with the processing circuitry, determining a total gain ratio by combining the global gain ratio and the local gain ratio. 
 
     
     
       2. The method defined in  claim 1 , wherein the first image has a mean intensity, the method further comprising:
 with the processing circuitry, adjusting the mean intensity by multiplying the mean intensity by the total gain ratio. 
 
     
     
       3. The method defined in  claim 1 , wherein the first image has a mean intensity, the method further comprising:
 with the processing circuitry, adjusting the mean intensity by dividing the mean intensity by the total gain ratio. 
 
     
     
       4. The method defined in  claim 1 , wherein determining the total gain ratio comprises multiplying the global gain ratio by the local gain ratio. 
     
     
       5. The method of  claim 1 , further comprising:
 with the processing circuitry, determining a spatial offset correction to the local gain ratio using a sum-of-absolute-differences procedure. 
 
     
     
       6. A method of producing gain-matched, color-matched stereoscopic images using a stereoscopic imaging device wherein the stereoscopic imaging device comprises a stereoscopic display, processing circuitry, and a stereoscopic imager having a first image module and a second image module, the method comprising:
 with a calibration apparatus, generating a color-calibration offset between the first image module and the second image module; 
 capturing a first image with the first image module and a second image with the second image module, wherein the first image and the second image have a common overlapping portion, and wherein the first image has a first mean intensity and the second image has a second mean intensity; 
 with the processing circuitry, determining a global gain ratio and a local gain ratio between the first and second images; 
 with the processing circuitry, determining a total gain ratio between the first and second images by combining the global gain ratio and the local gain ratio; and 
 adjusting the first mean intensity based on the total gain ratio. 
 
     
     
       7. The method defined in  claim 6 , further comprising:
 with the processing circuitry, determining a first color-transformation matrix associated with the first image module and a second color-transformation matrix associated with the second image module, wherein the second color-transformation matrix is at least partially determined using the color-calibration offset. 
 
     
     
       8. The method defined in  claim 6 , further comprising:
 with the processing circuitry, collecting a first set of automatic white balance statistics associated with the first image and a second set of automatic white balance statistics associated with the second image. 
 
     
     
       9. The method defined in  claim 8 , further comprising:
 with the processing circuitry, determining a first color space associated with the first image using the first set of automatic white balance statistics; and 
 with the processing circuitry, determining a second color space associated with the second image using the second set of automatic white balance statistics. 
 
     
     
       10. The method defined in  claim 9 , wherein the stereoscopic display has a display color space, the method further comprising:
 with the processing circuitry, transforming the first color space associated with the first image to the display color space using the first set of automatic white balance statistics and the first color-transformation matrix. 
 
     
     
       11. The method defined in  claim 10 , the method further comprising:
 with the processing circuitry, transforming the second color space associated with the second image to the display color space using the second set of automatic white balance statistics and the second color-transformation matrix. 
 
     
     
       12. A method of producing gain-matched, color-matched stereoscopic images using a stereoscopic imaging device wherein the stereoscopic imaging device comprises a stereoscopic display, processing circuitry, and a stereoscopic imager having a first image module and a second image module, the method comprising:
 with a calibration apparatus, determining a first color-calibration offset between the first image module and a gold standard image module; and 
 with the calibration apparatus determining a second color-calibration offset between the second image module and the gold standard image module. 
 
     
     
       13. The method defined in  claim 12 , further comprising:
 capturing a first image with the first image module and a second image with the second image module, wherein the first image and the second image have a common overlapping portion. 
 
     
     
       14. The method defined in  claim 13 , further comprising:
 with the processing circuitry, determining a first color-transformation matrix associated with the first image module, wherein the first color-transformation matrix is at least partially determined using the first color-calibration offset. 
 
     
     
       15. The method defined in  claim 14 , further comprising:
 with the processing circuitry, determining a second color-transformation matrix associated with the second image module, wherein the second color-transformation matrix is at least partially determined using the second color-calibration offset. 
 
     
     
       16. The method defined in  claim 15 , wherein the stereoscopic display has a display color space, the method further comprising:
 with the processing circuitry, determining a first color space associated with the first image and a second color space associated with the second image; 
 with the processing circuitry, transforming the first color space associated with the first image to the display color space using the first color-transformation matrix; and 
 with the processing circuitry, transforming the second color space associated with the second image to the display color space using the second color-transformation matrix. 
 
     
     
       17. The method defined in  claim 16 , wherein the second image has a mean intensity, the method further comprising:
 with the processing circuitry, determining a total gain ratio between the first and second images; and 
 with the processing circuitry, adjusting the mean intensity based on the total gain ratio.